Question

I know the following function can be used to do some pre-save processing. But, how can I access the request data, for example a text field value from the request for doing validation?

    def save_model(self, request, obj, form, change):
        # do something for validation 
        obj.save()

Answer 1

The raw request data is stored in request.POST, as it usually is. It’s probably better to access form.cleaned_data, as Django has already validated it.

However, the save_model method probably isn’t the correct place to do validation. If you raise a ValidationError, then the exception will not be caught and the user will get a 500 server error page. The save_model method is more appropriate when you know the data is already valid, for example to set the object’s author based on request.user before saving.

If you want to do custom validation, a better approach would be to define a model form, and use it in your model admin with the ModelAdmin.form setting.